. Discovery. Science. MARKING MADE WITH METALLIC LEAD. Fig. 3 Magnification Fig. 2.—marking made with LEAD PENCIL CONTAINING BORROWDALE Period 1831. Magnification 20. Fig. 3.—marking made with pencil of COMPRESSED GRAPHITE. Period 1843. Magnification 20. and fourteenth centuries ruled lines similar to those described by Schonemann are present, and in each case they are in a pigment of metallic lead or other metal. All the early pencil writing in annotations in books in the Bodleian is in a pigment of metal. Notable instances of such writing are to be found in the horn notebook of Cas
. Discovery. Science. MARKING MADE WITH METALLIC LEAD. Fig. 3 Magnification Fig. 2.—marking made with LEAD PENCIL CONTAINING BORROWDALE Period 1831. Magnification 20. Fig. 3.—marking made with pencil of COMPRESSED GRAPHITE. Period 1843. Magnification 20. and fourteenth centuries ruled lines similar to those described by Schonemann are present, and in each case they are in a pigment of metallic lead or other metal. All the early pencil writing in annotations in books in the Bodleian is in a pigment of metal. Notable instances of such writing are to be found in the horn notebook of Casaubon (1613) and in the diaries of Anthony Wood (1676-85). Pencils of natural graphite, made by cutting the mineral into strips which were in a wooden holder, produce lines which show masses of brown or black pigment, whilst in heavier strokes the fibres of the paper are lit up by the adhering particles. Occasionally particles of siliceous impurities will occur, and will produce irregular disjointed striations appear- ing white on the dark background of the pigment, as shown in Fig. 2. The first occurrence noted of writing in a graphite pencil in the Bodleian Library is in a note made by Anthony Wood in A Collection of Poems on Affairs of State (168S). The masses of pigment are quite uniformly distributed and none of them shows the lustre or striations of the particles left by lead or other metals. The earliest instances of graphite writing discovered in the British Museum were in two notebooks of Sir Thomas Cotton, one of about 1630 to 1640, and the other 1640 to 1644. Other interesting examples in the British Museum are to be found in Hogarth's notebook, the pencil marks in which are particularlv free from any siliceous striations, and in Flaxman's drawings of the early nineteenth century, \\hich are in an exceedingly fine type of graphite. The gradual failure of the Borrowdale graphite mines led to the adoption of various sub- stitutes. In the first place, graphit
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